A conventional electromagnetic actuator for opening and closing a valve of an internal combustion engine generally includes "open" and "close" electromagnets which, when energized, produce an electromagnetic force on an armature. The armature is biased by a pair of identical springs arranged in parallel. The armature is coupled with a cylinder valve of the engine. The armature rests approximately half-way between the open and close electromagnets when the springs are in equilibrium. When the armature is held by a magnetic force in either the closed or opened position (at rest against the open or close electromagnet), potential energy is stored by the springs. If the magnetic force is shut off with the armature in the opened position, the spring's potential energy will be converted to kinetic energy of the moving mass and cause the armature to move towards the close electromagnet. If friction is sufficiently low, the armature can then be caught in the closed position by applying current to the close electromagnet.
The open and close electromagnets of the above-described conventional electromagnetic actuator each include a lamination core assembly coupled to a housing. A coil is associated with each core assembly. Typically, the core assembly is composed of a plurality of individual laminations which are joined to define the core assembly. The core assembly is typically secured to the housing by straight pins. However, with straight pins, it is difficult to achieve a strong interference fit on both ends of the pin because the large installation force exerted on the pin can cause the pin to plastically deform. Further, the pins alone are not sufficient to prevent centrally located laminations of the core assembly from being forced in a direction away from the housing during operation of the of the actuator.
There is a need to provide a lamination core assembly-housing connection which is easy to manufacture, provides intimate contact between the housing and core assembly to facilitate heat transfer, and which prevents movement of the central portion of the core assembly when force is exerted thereon.